Flagship Pioneering launched Serif Biomedicines with a $50 million debut to pursue what it describes as “modified DNA” medicines designed to durably express therapeutic proteins without altering a patient’s genome. The startup is built around delivering two components: a DNA instruction set and supporting mRNA “co-factors,” packaged for cellular uptake via lipid nanoparticles. Serif claims its approach can bypass limitations seen in other genetic medicine modalities, including the risks that can come with integrating or editing DNA in the genome. The company said it aims for repeat dosing and broader tissue targeting compared with viral delivery systems commonly used in gene therapy. Serif plans to present preclinical data at an upcoming medical meeting and said it is initially focusing on rare genetic diseases and immunology. The launch comes as cell and gene therapy investors remain selective about development cost and commercialization pathways.